Soft contact lenses, ordinarly made of poly 2-hydroxyethyl methacrylate, polyvinyl pyrrolidone, or the like, have become quite popular with eyeglass wearers, and particularly those who need optical correction for near-sightedness. While in part such wear is cosmetic in nature, they are conceded to be more comfortable for prolonged wear than "hard" contact lenses. Additionally, the material from which soft contact lenses are formed is virtually unbreakable and minimize the hazard of damage to the wearer's eyes, as compared to hard contact lenses. Unfortunately, these materials are porous and readily absorb liquids. In fact, this type of material depends for its softness upon the fact that it does absorb liquid, including the natural tear fluid of the eyes. Because of this porous characteristic, they also readily absorb bacteria, molds and yeasts in normal wear, and require sterilization on a regular basis. Recommended sterilization is at least daily, if the wearer is to avoid possible eye infections. In the cleaning process, it is necessary that the lenses be removed and placed in a sterilizing solution or steamed, according to the prior art, for a period of time sufficient to assure kill of the microorganisms. Unfortunately, in removal and sterilizing, the contact lenses normally develop scratches and abraded spots in the lens surface due to fingernails and other rough surfaces. Such imperfections in the surfaces add to the possibility of microorganism growth in the material.
It is, of course, essential that the material not dry out, because, if dry, it tends to change dimensions and crack. Accordingly, the contact lenses must be sterilized while wet, or at least moist. It has been proposed heretofore to sterilize such articles with ethylene oxide in a gaseous state. (See for example in U.S. Pat. No. 3,473,886, Leeds, or U.S. Pat. No. 2,965,936, Kaye.) However, ethylene oxide gas is not particularly effective in sterilizing water-wet materials and additionally, because ethylene oxide is a reactive gas, it may interact with the material to cause deterioration. As mentioned before, the use of sterilizing liquids, such as hydrogen peroxide solutions (recommended for polyvinyl pyrrolidone-containing lenses) is undesirable because such sterilization requires a prolonged period of time (several hours). Further, if hydrogen peroxide is retained in the porous surface of the soft contact lens, it has a tendency to dehydrate the eyes and may cause irritation. In addition, unless the concentration of the solution is high, it is not fully effective as a sterilizing agent.
The most popular system for cleaning soft contact lenses at the present time is to steam the lenses for, say, 15 to 20 minutes after they have been thoroughly washed in a saline solution, freshly made, using distilled water. Sterilizing is normally carried out in a steam generator by evaporating distilled water. The difficulty of obtaining a suitable source of heat, such as electrical power, and the necessity for carrying a supply of distilled water and salt, renders the method effective only under the most stable living conditions for the user. In particular, in traveling or moving about, the user frequently finds such apparatus and materials quite inconvenient for regular daily use.